1. Field of the Invention
The present invention relates to testing apparatus for an electronic ignition system for an internal combustion engine and, more particularly, to testing apparatus for dynamically driving electronic ignition systems throughout their entire RPM ranges.
2. Description of the Prior Art
Electronic ignition systems are becoming increasingly more popular in automobiles and other vehicles. By eliminating the mechanical points, they operate more dependably and accurately and for longer periods of time. On the other hand, these systems are extremely complex, are usually packaged in a single amplifier module, and are difficult for even a skilled mechanic to check and test. When the vehicle's engine malfunctions or ceases to operate, the electronic ignition system necessarily becomes suspect.
A mechanic can chose from a multiplicity of equipments to test almost every separate piece of each system installed on an engine, such as fuel, mechanical and electrical parts, with or without the engine running. However, there has been no way of testing the actual dynamic operation of the electronic ignition system unless the vehicle's engine is operating. Unfortunately, very often, the engine will not operate and it is difficult to isolate the source of the problem.
A number of attempts have been made to solve this problem. It has been proposed to simulate the actual operating conditions of an electronic ignition system to evaluate operation and isolate problems. One known system includes a trigger simulation device, including a trigger pulse generator and an amplifier, for externally simulating the trigger pulses generated by the distributor magnetic sensor. This pulse is then applied to the electronic ignition system and the operation of the system monitored. However, such system requires an external generator to simulate the operation of the engine and disconnection of the input connection from the distributor magnetic sensor to the electronic control unit.
U.S. Pat. No. 4,101,822 describes a self-contained, portable unit which does not require any auxiliary power supply for testing breakerless ignition systems. A simulator circuit is provided to simulate a signal representative of the signal obtained by the rotation of a timing cam as the timing cam traverses a magnetic sensor. Again, the approach of this patent is to bypass the magnetic sensor and to inject an artificial signal directly into the ignition system.
U.S. Pat. No. 4,186,337 also discloses testing apparatus for performing voltage, continuity, open circuit or dynamic signal substitution testing of each individual major component within an automotive-type transistor ignition system. However, in order to use this device, one must disconnect each component and separately simulate some signal to it, or receive some signal from it.